Acoustic panels typically comprise a honeycomb core layer trapped between a solid bottom skin and an upper skin. The upper skin is typically perforated with a plurality of acoustic holes to trap the sound in the alveolar cells of the honeycomb material. Accordingly, for the acoustic panels to perform satisfactorily, obstruction or contamination of the acoustic holes should be avoided. This might be challenging when the acoustic panels have to be integrated to an engine structure which necessitates the panels to be exposed to manufacturing processes, such as welding and machining. There is always a risk that some of the acoustic holes become clogged or contaminated as a result of being exposed to such subsequent manufacturing processes. Cleaning the panels afterwards can be challenging. Accordingly, the integration of acoustic panels in certain areas of gas turbine engines is still relatively limited.